I believe underwriters labortories requires special valve train designs that includes special safety devices when a gas appliance is over 400,000 btus. Would Ul's requirement superceed state gas codes and is 400,000 btus be the standard for what would be concidered "Large Appliances". I will contact the fuel boad next week but was wondering if anyone has any ideas or experience in that area.

Thank you



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Whaat are you creating that you need to know the answer to this?

A 500,000 btu gas boiler with a factory gas valve and no additional safetys.

I can't speak to the requirements, but to the best of my knowledge, the gas valve is just that, a valve. The safeties are in the control for the valve. I've never heard of different sized boilers having different safety requirements. They all require that the appliance not kill anyone.Put a shout out to Tim McElwain at heatinghelp.com. He will be able to answer your specific questions. He runs a gas training facility in Rhode Island.



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IF the "safeties" were not installed on the boiler, you should NOT be installing it unless you are competent to do EVERYTHING required for safe operation. The majority of safeties WILL turn off the gas system, but there are other requirements also.

Thank you I wll make sure things are done correctly.